tq max and min delay

setup and hold relationships

1.　　default

2.　　multicycles　　　　: choose different clock edges of the existing waveforms.

3.　　max and min　　　: modify setup and hold relationships to arbitrary values.

max and min

device-centric constraints

system-centric constraints

max min as substitutes for these device-centric constraints

not designed to be I/O relationship

low-level constraints that override the default setup and hold